1. Field of the Disclosure
The present disclosure generally relates to the field of transport systems, in particular of coating systems, in which objects, in particular substrates such as semiconductor wafers, solar cells, etc. and/or substrate carriers should be strung together.
2. Discussion of the Background Art
When coating flat objects such as, e.g., substrates, it is necessary that the objects on the one hand remain statically in a specific position in a coating system for a certain time, for example for heating them. On the other hand, it is necessary that the objects are moved past the coating source at a constant speed. In connection with the movement past the coating source it is desirable that the objects pass the coating source with as little gaps as possible between them, so that as little as possible of the material to be applied does not reach the object and enters the coating chamber.
The stringing together of the objects, i.e. the lining of the objects one behind the other, is often controlled by sensors which are arranged at corresponding positions and should serve for detecting an approaching object. In this regard, the approximate speed and the approximate time are additionally required for determining or influencing the distance or gap between the preceding object and the successive object. In order to prevent the objects from colliding, a certain safety distance must be maintained. However, in particular in coating systems it is desired, as mentioned above, to keep this distance as small as possible.
When using carriers for the objects, the distance can be adjusted reliably, e.g., by a connection (groove and tongue at the carriers) between the carriers moving one behind the other. However, this principle functions only if specific carriers are used. Hence, it is not possible to apply this principle to objects moving through such a system without carriers.
In view of the prior art, reference is further made to DE 10 2009 050 328 A1 and DE 10 2010 031 245 A1.
The solutions available so far are not reliable and allow only relatively large distances between the objects.